Speaking to the German newspaper Bild, Rummenigge said, “It is well-known, that the Borussia Dortmund player (Reus) has a release clause, which, according to rumours, lies at €25 million.”

Borussia Dortmund were sure to be infuriated by Rummenigge’s outspoken comments, especially after Bayern Munich have already bought Mario Gotze and Robert Lewandowski in recent transfer windows – players who were pivotal to Dortmund’s 2011/2012 Bundesliga winning side.

Sure enough, Borussia Dortmund CEO Hans-Joachim Watzke didn’t bite his tongue on the matter. In response to Rummenigge’s comments, the Dortmund chief stated, “Borussia Dortmund has noted with some irritation that Karl-Heinz Rummenigge is currently discussing internal BVB matters in the media.”

He then furthered to declare, “Karl-Heinz Rummenigge is also fully aware that his behaviour is only going to further damage an already tense relationship between Borussia Dortmund and Bayern Munich.”

Ever since Dortmund’s title winning season in 2011/2012, a tale rid of reciprocity on Bayern Munich’s part has led to a prolonging feud between the two clubs; Dortmund feel Bayern have abused their rich history and wealth into luring Dortmund players to the club.

However, Reus previously responded to transfer speculation in October 2013, stating, “I live in the here and now and therefore I am delighted to be a player of Borussia Dortmund. I am under contract with the club until June 2017. Everything else is irrelevant, from my point of view."

As Watzke hinted, only the cut of a knife is needed to ignite the tension between the two clubs. Whether Reus is that knife remains to be seen.